The need for ignition enablement-disablement devices for a variety of equipment is well known. Such devices serve to make ignition of drive engines impossible unless the drive controls are in a neutral condition. These devices are used in connection with vehicle transmissions, in connection with drive controls for various implements powered by vehicle drive engines, and on drive controls for a variety of other powered mechanisms.
A good example of the sort of equipment for which such ignition enablement-disablement devices are highly important is the hydrostatic drive controls for a trencher. It is required that ignition of the drive engine be disabled for such equipment unless the trencher mechanism and vehicle transmission are in neutral. Such ignition disablement devices serve to prevent unintended lurching movements of the vehicle and/or the trencher.
A wide variety of devices are used for ignition enabling-disabling purposes. Some of such devices include what may be referred to as neutral start switches, that is, an electrical switch which is in a closed position only when the drive control is in a neutral position. This invention is an improvement in ignitiion enablement-disablement devices of the type having neutral start switches.
Some of the prior devices of this type have significant disadvantages and drawbacks. Certain devices are cam operated, and because of vibration, dirt and other conditions, such devices are often susceptible to excessive wear which can lead to breakage of parts and possible malfunction. Some devices require location in particular positions vis-a-vis the drive control, in some cases limiting their application. Some devices are located in rather inaccessible positions which, among other things, make maintenance problematic. Some devices are rather complex in structure and operation.
There is a need for an improved simple and effective device which renders the starting circuit inoperative whenever a drive control is out of its neutral position.